EPA Zone Data 2026
CA Radon Levels
View EPA radon zone classifications for every county in CA. Select your county to see detailed risk data, testing recommendations, and mitigation cost estimates.
2
Zone 1
High Risk
High Risk
29
Zone 2
Moderate
Moderate
27
Zone 3
Low Risk
Low Risk
Alameda
Zone 2
Alpine
Zone 2
Amador
Zone 2
Butte
Zone 3
Calaveras
Zone 2
Colusa
Zone 3
Contra Costa
Zone 2
Del Norte
Zone 3
El Dorado
Zone 2
Fresno
Zone 2
Glenn
Zone 3
Humboldt
Zone 3
Imperial
Zone 3
Inyo
Zone 2
Kern
Zone 2
Kings
Zone 3
Lake
Zone 3
Lassen
Zone 3
Los Angeles
Zone 2
Madera
Zone 2
Marin
Zone 3
Mariposa
Zone 2
Mendocino
Zone 3
Merced
Zone 3
Modoc
Zone 3
Mono
Zone 2
Monterey
Zone 2
Napa
Zone 3
Nevada
Zone 2
Orange
Zone 3
Placer
Zone 2
Plumas
Zone 2
Riverside
Zone 2
Sacramento
Zone 3
San Benito
Zone 2
San Bernardino
Zone 2
San Diego
Zone 3
San Francisco
Zone 2
San Joaquin
Zone 3
San Luis Obispo
Zone 2
San Mateo
Zone 2
Santa Barbara
Zone 1
Santa Clara
Zone 2
Santa Cruz
Zone 2
Shasta
Zone 3
Sierra
Zone 2
Siskiyou
Zone 3
Solano
Zone 3
Sonoma
Zone 3
Stanislaus
Zone 3
Sutter
Zone 3
Tehama
Zone 3
Trinity
Zone 3
Tulare
Zone 2
Tuolumne
Zone 2
Ventura
Zone 1
Yolo
Zone 3
Yuba
Zone 2
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